deletions

Deletions are losses of material from a system. In genetics, a deletion is a mutation in which a segment of DNA is missing. Deletions can affect single genes or larger chromosomal regions, with effects ranging from benign variation to severe disease depending on size and which genes are lost. Mechanisms include errors during DNA replication, unequal crossing over during meiosis, or recombination between repetitive sequences. Large deletions called chromosomal deletions can involve many genes and are detectable by cytogenetic methods; smaller, gene-level deletions are identified by sequencing or microarray analyses. In population genetics, deletions are among the class of structural variants that shape genomes.

In language and text editing, deletion means removing letters, syllables, words, or larger passages. In phonology and speech, elision is the omission of sounds in casual pronunciation. In writing, deletions may improve clarity or accuracy but can also alter nuance or meaning.

In computing and information technology, deletion refers to removing data or objects. Users may delete files to reclaim storage; many systems move deleted items to a recycle bin or trash before permanent removal. Secure deletion attempts to prevent recovery by overwriting data. Databases provide delete operations to remove records; file systems may handle metadata and permissions to manage deletion.

Deletions are thus encountered across biology, language, and technology as losses of material, information, or content, with implications for function, communication, and data management.